Count of Blackfin core clock cycles

Q

How can we count Blackfin core clock cycles? CYCLES and CYCLES2 don't seem to
count anything (their value is always zero!)

A

The reason the cycle counter does not see to be working is because it has not
been enabled. From the VisualDSP++ On-Line help: "To enable the cycle counters,
set the CCEN bit in the SYSCFG register. The following example shows how to
use the cycle counter:

R2 = 0;
CYCLES = R2;
CYCLES2 = R2;
R2 = SYSCFG;
BITSET(R2,1);
SYSCFG = R2;
/* Insert code to be benchmarked here. */
R2 = SYSCFG;
BITCLR(R2,1);
SYSCFG = R2;
"

This works for both simulator and emulator.